Chewing Well Modulates Pharyngeal Bolus Transit During Swallowing in Healthy Participants.

Mastication is controlled by central pattern generator in the brainstem and can be modulated by volition. The aim of this study was to investigate the effect of chewing well on swallowing. Twenty-six healthy participants were instructed to eat 8, 12, and/or 16 g of steamed rice with barium sulphate under the following two conditions: chewing freely task (CF; chewing naturally in their usual manner) and chewing well task (CW; chewing the food with a request to "chew well"). We evaluated bolus transport and swallowing movement using videofluoroscopy and electromyography of the masseter, suprahyoid and thyrohyoid muscles. The chewing time and pharyngeal transit time (PTT) at the first swallow showed high reproducibility in both CF and CW. PTT for CW was significantly shorter and longer than CF in 12 and 16 g, respectively. In 12 g, CW increased the pharyngeal bolus velocity and decreased thyrohyoid EMG activity during swallowing compared with CF. In 16 g, the difference between CW and CF in the estimated swallowed bolus volume was positively correlated with that in upper esophageal sphincter transit duration. We speculate that CW modulates PTT during swallowing depending on the mouthful volume.

Continuous electrical stimulation of superior laryngeal nerve inhibits initiation of swallowing in anesthetized rats.

Pharyngeal electrical stimulation (PES) applies electrical stimulation to pharyngeal mucosa (PhM) and represents a useful approach to improve swallowing function in patients with dysphagia. To determine the optimal PES modality to treat dysphagia, the mechanism underlying the effects of PES on swallowing function must be elucidated. In this study, we evaluated how PES and electrical stimulation of the superior laryngeal nerve (SLN) modulate the initiation of swallowing in anesthetized rats. A swallow was evoked by electrical stimulation of the PhM, SLN, and nucleus of the solitary tract (nTS) and pharyngeal mechanical stimulation using a von Frey filament. A swallow was identified by electromyographic bursts in mylohyoid and thyrohyoid muscles. Bilateral SLN transection abolished the swallows evoked by PhM electrical stimulation. PhM and SLN electrical stimulation decreased swallowing frequency in a similar time-dependent manner. Intravenous administration of the GABAA receptor antagonist bicuculine did not affect the time-dependent change in swallowing frequency during SLN electrical stimulation. Continuous SLN electrical stimulation significantly inhibited pharyngeal mechanically and nTS-electrically evoked swallows compared with before and 5 min after stimulation. The present findings suggest that the SLN plays a primary role in PES-evoked swallows. Additionally, continuous SLN electrical stimulation inhibits the initiation of swallowing, and the modulation of central network associated with swallowing might be partially involved in this inhibition.

Short-term and long-term effects of unilateral external carotid artery ligation on orofacial functions in rats.

The external carotid artery (ECA) plays a major role in supplying blood to the head and neck. Although impeded blood flow in the ECA is expected to affect orofacial functions, few studies have shown how blood flow obstruction in the ECA contributes to impairment of these functions, including chewing and swallowing. This study was performed to investigate the effects of ECA ligation (ECAL) on immediate and long-term changes in masticatory and swallowing functions as well as the jaw-opening reflex evoked in the digastric muscle. The experiments were carried out using male Sprague-Dawley rats. In the acute experiment, the digastric reflex evoked by low-threshold electrical stimulation of the inferior alveolar nerve and the swallow reflex, identified by digastric and thyrohyoid electromyographic (EMG) bursts, were compared between before and 1 h after ECAL. The chronic experiment was conducted on freely moving rats. EMGs of the masseter, digastric, and thyrohyoid muscles were chronically recorded. The long-term effects of ECAL on behavior and muscle histology were compared between rats with an intact ECA and rats with ECAL. In the acute experiment, the peak amplitude of the digastric reflex on the ECAL side was significantly decreased 1 h after ECAL. In the chronic experiment, although most parameters of the masticatory and swallowing EMGs were not significantly different between the groups, the results suggest wide variation of the effect of ECAL on the muscles. Blood supply compensation from collaterals of the internal carotid artery may be permanent in some animals.NEW & NOTEWORTHY The inhibitory effect of unilateral external carotid artery ligation (ECAL) on the ipsilateral digastric reflex was small but evident. Most parameters of masticatory and swallowing muscle activity were not significantly different after ECAL. Wide variation was noted in the effect of ECAL on the ipsilateral muscle activity. Blood supply compensation from collaterals of the internal carotid artery may occur in response to the impaired blood flow.

Use of suction electrodes for measurement of intrinsic tongue muscular endurance during lingual pressure generation.

BACKGROUND: Lingual pressure (LP) generation is cooperatively controlled not only by the intrinsic tongue (I-ton) muscles but also by hyoid muscle activation. However, the measurement of endurance and fatigue properties of I-ton muscles is difficult due to the instability of electrodes. OBJECTIVE: The purpose of this study was to apply suction electrodes to measure electromyograms (EMGs) of I-ton muscle and to evaluate integrated EMG amplitude (iEMG) and mean power frequency (MPF) of EMG in the I-ton and hyoid muscles performing continuous LP. METHODS: Twenty healthy adult volunteers (10 males, 10 females, mean age 28.8 years) were instructed to perform 10-s LP generation tasks at 25%, 50%, 75% and 100% of maximum LP in randomised order with visual feedback. During each task, EMGs of the I-ton, suprahyoid (S-hyo), infrahyoid (I-hyo) and masseter (Mass) muscles were simultaneously recorded. The iEMG and MPF of EMG burst during 10-s LP tasks were compared. The recording period was divided into three substages to analyse temporal changes with the Friedman test. RESULTS: During the 10-s task, the iEMG significantly increased as the LP strength increased (p < .001). There was no time-dependent change in the I-ton iEMG; however, the MPF of the I-ton EMG burst decreased in all tasks (p < .05). The S-hyo and I-hyo iEMGs gradually increased, especially with strong LP (p < .01). CONCLUSION: While I-ton muscles may easily fatigue during 10-s LP generation, S-hyo and I-hyo muscles may help compensate for the weakened I-ton muscle activity by increasing their activity to maintain LP.

Modulation of reflex responses of the anterior and posterior bellies of the digastric muscle in freely moving rats.

BACKGROUND: Chewing and licking are primarily activated by central pattern generator (CPG) neuronal circuits in the brainstem and when activated trigger repetitive rhythmic orofacial movements such as chewing, licking and swallowing. These CPGs are reported to modulate orofacial reflex responses in functions such as chewing. OBJECTIVE: This study explored the modulation of reflex responses in the anterior and posterior bellies (ant-Dig and post-Dig, respectively) of the digastric muscle evoked by low-intensity trigeminal stimulation in conscious rats. METHODS: The ant-Dig and post-Dig reflexes were evoked by using low-intensity electrical stimulation applied to either the right or left inferior alveolar nerve. Peak-to-peak amplitudes and onset latencies were measured. RESULTS: No difference was observed between threshold and onset latency for evoking ant-Dig and post-Dig reflexes, suggesting that the latter was also evoked disynaptically. The peak-to-peak amplitude of both reflexes was significantly reduced during chewing, licking and swallowing as compared to resting period and was lowest during the jaw-closing phase of chewing and licking. Onset latency was significantly largest during the jaw-closing phase. Inhibitory level was similar between the ant-Dig and post-Dig reflex responses and between the ipsilateral and contralateral sides. CONCLUSION: These results suggest that both the ant-Dig and post-Dig reflex responses were significantly inhibited, probably due to CPG activation during feeding behaviours to maintain coordination of jaw and hyoid movements and hence ensure smooth feeding mechanics.

Effects of Head and Neck Alignment and Pharyngeal Anatomy on Epiglottic Inversion During Swallowing in Dysphagic Patients.

The effects of head and neck alignment and pharyngeal anatomy on epiglottic inversion remain unclear. This study investigated the factors involved in epiglottic inversion, including head and neck alignment and pharyngeal anatomy, in patients with dysphagia. Patients with a chief complaint of dysphagia and who underwent videofluoroscopic swallowing study at our hospital from January to July 2022 were enrolled. They were divided into three groups based on the degree of epiglottic inversion as the complete-inversion (CI), partial-inversion (PI), and non-inversion group (NI) groups. Data were compared among the three groups; a total of 113 patients were analyzed. The median age was 72.0 (IQR: 62.0-76.0) years; 41 (36.3%) and 72 (63.7%) were women and men, respectively. There were in 45 (39.8%) patients in the CI, 39 (34.5%) in the PI, and 29 (25.7%) in the NI groups, respectively. Single-variable analysis revealed significant relation to epiglottic inversion of Food Intake LEVEL Scale score, penetration-aspiration score with 3-mL thin liquid bolus, epiglottic vallecula and pyriform sinus residue, hyoid position and displacement during swallowing, pharyngeal inlet angle (PIA), epiglottis to posterior pharyngeal wall distance, and body mass index. Logistic regression analysis with complete epiglottic inversion as the dependent variable revealed the X coordinate at maximum hyoid elevation position during swallowing and PIA as significant explanatory variables. These results suggest that epiglottic inversion is constrained in patients with dysphagia who have poor head and neck alignment or posture and a narrow pharyngeal cavity just before swallowing.

Atropine facilitates water-evoked swallows via central muscarinic receptors in anesthetized rats.

Anticholinergic medication causes impaired swallowing with hyposalivation. However, the underlying mechanisms by which these drugs modulate the swallowing reflex remain unclear. This study investigated the effects of the muscarinic acetylcholine receptor (mAChR) nonspecific antagonist atropine on the initiation of swallowing. Experiments were performed on 124 urethane-anesthetized rats. A swallow was evoked by either topical laryngeal application of a small amount of distilled water (DW), saline, citric acid, or capsaicin; upper airway distention with a continuous airflow; electrical stimulation of the superior laryngeal nerve (SLN); or focal microinjection of N-methyl-d-aspartate (NMDA) into the lateral region of the nucleus of the solitary tract (L-nTS). Swallows were identified by electromyographic bursts of the digastric and thyrohyoid muscles. Either atropine, the peripheral mAChR antagonist methylatropine, or antagonists of mAChR subtypes M1-M5 were intravenously delivered. Atropine at a dose of 1 mg/kg increased the number of DW-evoked swallows compared with baseline and did not affect the number of swallows evoked by saline, citric acid, capsaicin, or upper airway distention. Methylatropine and M1-M5 antagonists did not significantly change the number of DW-evoked swallows. Bilateral SLN transection completely abolished DW-evoked swallows, and atropine decreased the swallowing threshold of SLN electrical stimulation. Finally, microinjection of NMDA receptor antagonist AP-5 into the L-nTS inhibited DW-evoked swallows, and atropine facilitated the initiation of swallowing evoked by NMDA microinjection into this region. These results suggest that atropine facilitates DW-evoked swallows via central mAChR actions.NEW & NOTEWORTHY Atropine facilitated the distilled water (DW)-evoked swallows in anesthetized rats. Atropine decreased the swallowing threshold evoked by electrical stimulation of the superior laryngeal nerve, which is a primary sensory nerve for the initiation of DW-evoked swallows. Atropine facilitated the swallows evoked by N-methyl-d-aspartate microinjection into the lateral region of the nucleus of the solitary tract, which is involved in the DW-evoked swallows. We speculate that atropine facilitates the DW-evoked swallows via central muscarinic receptor actions.

Inhibition of Water-Evoked Swallowing During Noxious Mechanical Stimulation of Tongue in Anesthetized Rats.

Dysphagia is sometimes accompanied by pain. Because orofacial structures subserve mastication and swallowing, orofacial pain might impair both functions. Tongue biting can occur not only accidentally while eating but also in some pathological conditions. However, it remains unclear whether noxious mechanical stimulation of the tongue affects swallowing. To explore this question, we evaluated the effects of lingual pinch stimulation on the initiation of swallowing evoked by distilled water (DW) infusion with a flow rate of 5.0 µL/s for 20 s into the pharyngolaryngeal region in anesthetized rats. The swallowing reflex was identified by electromyographic (EMG) bursts in the suprahyoid muscles which include the anterior belly of the digastric muscle, mylohyoid and geniohyoid muscles, and laryngeal elevation by visual inspection. The number of DW-evoked swallows during pinch stimulation was significantly smaller than that in a control condition or during pressure stimulation. The onset latency of the first swallow during pinch stimulation was significantly longer than that in the control condition. DW-evoked swallowing was almost abolished following bilateral transection of the superior laryngeal nerve (SLN) compared with the control condition, suggesting that the SLN plays a crucial role in the initiation of DW-evoked swallowing. Finally, electrophysiological data indicated that some SLN-responsive neurons in the nucleus tractus solitarii (nTS) exhibited delayed latency from a single SLN stimulation during lingual pinch stimulation. These results suggest that noxious mechanical stimulation of the tongue inhibits the initiation of swallowing and modulates neuronal activity in the nTS.

Evaluating the effect of management on patients with oral hypofunction: A longitudinal study.

INTRODUCTION: Declining oral function may affect subsequent physical frailty in the older population. The aim of this longitudinal study was to summarise data on patients who underwent functional oral examination and evaluate the impact of management on patients with oral hypofunction (OHF). METHODS: Dental outpatients aged over 65 years at their initial visit to the Niigata University Hospital received detailed assessment of seven oral function items to diagnose oral hypofunction using diagnostic criteria defined by the Japanese Society of Gerodontology. Patients with OHF at the first assessment received management including oral health guidance for low function and dental treatment. They were re-evaluated approximately 6 months later and the two assessments were compared. According to the results of the second assessment, the patients were divided into two groups: OHF improved and OHF re-diagnosed. RESULTS: Of the 273 patients who underwent the first assessment, 86 (31.5%) were diagnosed with OHF and received management. Of those, 42 (48.8%) completed the second assessment. Comparing the first and second assessment, significant improvement was observed in oral hygiene, occlusal force, tongue-lip motor function of /pa/, mastication and swallowing. The change in values from the first assessment demonstrated a significant difference between the OHF improved and re-diagnosed groups only in occlusal force. CONCLUSION: Management for patients with OHF can contribute to the improvement of poor oral function, and an increase in occlusal force was notable in the recovery from OHF.

Functional evaluation of jaw and suprahyoid muscle activities during chewing.

BACKGROUND: It has not yet been clarified how the type of the chewing task affects related muscle activity and how the suprahyoid muscles contribute to masticatory function in humans. OBJECTIVES: This study aimed to investigate the difference in the suprahyoid muscle activity between the freely and unilaterally chewing tasks and between the working and non-working sides during chewing. MATERIALS AND METHODS: Twenty healthy volunteers were instructed to chew peanuts and two different types of rice crackers in two ways: freely and unilaterally while surface electromyograms of the masseter and suprahyoid muscles were recorded. The chewing duration, number of chewing cycles and chewing rate were compared between the tasks. Furthermore, the masseter and suprahyoid muscle activities per chewing cycle were compared between the sides. RESULTS: The chewing duration was significantly longer, and the chewing rate was significantly higher during unilaterally chewing than freely chewing. The chewing duration differed significantly among the different foods; the harder the food, the longer the duration. Chewing rate and suprahyoid activity were significantly higher during soft rice cracker chewing. Masseter activity was higher on the chewing side than on the non-chewing side while there was no difference in suprahyoid activity between the sides. CONCLUSION: The current results demonstrate a difference in the masticatory efficacy between the chewing tasks and a functional role of the suprahyoid muscles during chewing, which does not differ between the chewing and non-chewing sides.

Functional Role of Suprahyoid Muscles in Bolus Formation During Mastication.

It still remains unclear how the suprahyoid muscles function in bolus formation during mastication. This study aimed to investigate the contributory role of the suprahyoid muscles during mastication. A total of 20 healthy young volunteers were asked to perform tongue pressure generation tasks and unilateral mastication tasks using peanuts and two different types of rice crackers. Surface electromyographic (EMG) activity of the masseter and suprahyoid muscles and mandibular kinematics were recorded. Suprahyoid activity increased with increasing tongue pressure. Masticatory duration until the first deglutition differed significantly among the different foods; the harder the food, the longer the duration. This was also the case in masseter activity per masticatory cycle. Masticatory rate and suprahyoid activity per masticatory cycle were significantly higher during soft rice cracker mastication. Masseter activity was higher on the masticatory side than on the non-masticatory side, however, there was no difference in suprahyoid activity between the sides. Suprahyoid activity and jaw gape showed significant positive correlation in the early stage on both the masticatory and non-masticatory sides. The suprahyoid muscles functioned dominantly for jaw-opening during peanut mastication, and for bolus formation, especially in the late stage during soft rice cracker mastication. Bolus formation was performed dominantly on the masticatory side during rice cracker mastication. These findings clearly demonstrate a functional role of the suprahyoid muscles during mastication of solid foods from assessments using both EMG activity and mandibular kinematic recordings.

Impact of oral function on regaining oral intake and adjusting diet forms for acute stroke patients.

BACKGROUND: Outcome prediction for dysphagia recovery is essential for rehabilitation treatment planning. Several studies have reported various predictors for resuming oral feeding after post-stroke dysphagia. However, evidence on oral health and function, a crucial part of feeding, has rarely been reported. Therefore, the goal of this study was to identify the oral status-related factors that could predict oral intake resumption in acute stroke patients. METHODS: 80 acute stroke patients with dysphagia were included. Clinical data, including the changes of general condition, oral and swallowing functions, were collected once a week until discharge. Patients were divided into two groups based on the outcome of the food intake level scale at discharge, and data were compared between the groups. RESULTS: 60 patients had regained complete oral intake before discharge. Multiple logistic regression showed that posterior tongue pressure could significantly predict complete oral intake recovery. Tongue pressure and modified water swallowing test score also significantly influenced diet forms. In addition, Spearman correlation analysis showed that improvement of other oral status-related factors, such as oral moisture and dentition status, also indicated the improvement of diet forms and swallowing function during the hospital stay. CONCLUSION: Tongue pressure measurement could be a useful oral status-related indicator for predicting complete oral intake and adjusting diet forms for acute stroke patients during hospitalization. Acute stroke patients should receive proper oral status evaluation and implementation to enhance functional recovery.

Chewing modulates the human cortical swallowing motor pathways.

When eating, mastication is always followed by swallowing. The present study assessed the effect of mastication on swallowing-related neural pathways in humans. Twenty healthy volunteers participated and underwent baseline transcranial magnetic stimulation to evaluate cortico-pharyngeal and cortico-hand motor-evoked potentials (MEPs). Next, they performed a chewing task and a swallowing task. Repeated-measures ANOVA revealed that pharyngeal MEPs were significantly higher after the swallowing task than after the chewing task, even though the number of swallows across tasks was matched. This implies that chewing movements suppress swallowing-related activity in the pharyngeal motor circuit.

Relationships Between Survival and Oral Status, Swallowing Function, and Oral Intake Level in Older Patients with Aspiration Pneumonia.

The factors affecting the survival of patients with aspiration pneumonia (AP) remain unclear. This study aimed to determine whether factors, including oral status, swallowing function, and oral intake level, were related to survival outcomes in older patients hospitalized for AP. The study enrolled patients with AP who were admitted to our hospital between February 2017 and November 2019. Patients were divided into two groups based on the 90-day mortality after the first swallowing function evaluation: survivors and deceased. The data were compared between the two groups. A total of 29 patients were diagnosed with AP. Of these patients, 13 died within 90 days. The numbers of patients who could not use removable dentures and required sputum suctioning and had cough reflex at rest were significantly higher in the deceased than in the survivors. The salivary pooling and pharyngeal clearance scores evaluated by videoendoscopy, International Dysphagia Diet Standardisation Initiative Functional Diet Scale score determined after swallowing function evaluation, and consciousness level were significantly worse in the deceased than in the survivors. There were significant differences in patients' oral status, swallowing function, oral intake level, and consciousness level between the survivors and deceased.

Rapid Onset of Weight Gain and Liver Dysfunction Successfully Treated With Nutrition and Exercise.

Physical inactivity is one of the causes of most metabolic syndromes. The incidence of metabolic syndrome is expected to increase in the near future because of the reduced opportunities for exercise caused by COVID-19. Non-alcoholic fatty liver disease (NAFLD) is currently the most common cause of chronic liver disease. Changes in diet and lifestyle have led to a dramatic increase in the prevalence of NAFLD in the world. NAFLD is characterized by excessive triglyceride (TG) accumulation in the hepatocytes due to both increased inflow of free fatty acids and de novo hepatic lipogenesis. Thus far, no study quantitatively assessed the liver fat deposition after a rapid decline in physical activity. Herein, we describe a case of a 17-year-old Japanese boy with severe fat infiltration of the liver, due to a rapid decline in physical activity, treated at our facility. Our rehabilitation and nutritional support teams administered appropriate exercise and nutrition support to reduce weight and improve liver dysfunction. Our findings support dietary changes and exercise therapy to manage such cases.

Survey of oral hypofunction in older outpatients at a dental hospital.

BACKGROUND: Oral hypofunction is defined as the reversible stage preceding oral dysfunction. However, its assessment and management need further examination and consideration. OBJECTIVE: The present study aimed to examine the current state of oral hypofunction among outpatients at the university hospital. METHODS: New outpatients underwent medical interviews and detailed assessment of oral hypofunction at their initial visit to our dental department. Oral hypofunction was diagnosed if the results of three of the following seven assessment items were below cut-off values: poor oral hygiene, oral dryness, reduced occlusal force, decreased tongue-lip motor function, decreased tongue pressure, decreased masticatory function and deterioration of swallowing function. The relationships between factors used to diagnose oral hypofunction as well as the distributions of assessment values were clarified. RESULTS: Seventy-five of 209 patients (35.9%) were finally diagnosed with oral hypofunction. Diagnosis of oral hypofunction was significantly related to patient age, Eichner index, a chief complaint of dental or periodontal disease or ill-fitting dentures and a history of neurodegenerative disease. The lowest quintile values for poor oral hygiene, oral dryness and decreased masticatory performance were all above current cut-off values. Reduced occlusal force contributed strongly to the diagnosis of oral hypofunction. CONCLUSION: Oral hypofunction in dental outpatients at a university hospital was associated with patient age, medical history and chief complaint at presentation. Diagnosis of oral hypofunction can be closely related to reduced occlusal force. The validity of cut-off values for assessments of oral hypofunction needs further consideration.

Coordination of Respiration, Swallowing, and Chewing in Healthy Young Adults.

Examining the coordination of respiration and swallowing is important for elucidating the mechanisms underlying these functions and assessing how respiration is linked to swallowing impairment in dysphagic patients. In this study, we assessed the coordination of respiration and swallowing to clarify how voluntary swallowing is coordinated with respiration and how mastication modulates the coordination of respiration and swallowing in healthy humans. Twenty-one healthy volunteers participated in three experiments. The participants were asked to swallow 3 ml of water with or without a cue, to drink 100 ml of water using a cup without breathing between swallows, and to eat a 4-g portion of corned beef. The major coordination pattern of respiration and swallowing was expiration-swallow-expiration (EE type) while swallowing 3 ml of water either with or without a cue, swallowing 100 ml of water, and chewing. Although cueing did not affect swallowing movements, the expiratory time was lengthened with the cue. During 100-ml water swallowing, the respiratory cycle time and expiratory time immediately before swallowing were significantly shorter compared with during and after swallowing, whereas the inspiratory time did not differ throughout the recording period. During chewing, the respiratory cycle time was decreased in a time-dependent manner, probably because of metabolic demand. The coordination of the two functions is maintained not only in voluntary swallowing but also in involuntary swallowing during chewing. Understanding the mechanisms underlying respiration and swallowing is important for evaluating how coordination affects physiological swallowing in dysphagic patients.

Antitussive effects of NaV 1.7 blockade in Guinea pigs.

Our previous studies implicated the voltage-gated sodium channel subtype NaV 1.7 in the transmission of action potentials by the vagal afferent nerves regulating cough and thus identified this channel as a rational therapeutic target for antitussive therapy. But it is presently unclear whether a systemically administered small molecule inhibitor of NaV 1.7 conductance can achieve therapeutic benefit in the absence of side effects on cardiovascular function, gastrointestinal motility or respiration. To this end, we have evaluated the antitussive effects of the NaV 1.7 selective blocker Compound 801 administered systemically in awake guinea pigs or administered topically in anesthetized guinea pigs. We also evaluated the antitussive effects of ambroxol, a low affinity NaV blocker modestly selective for tetrodotoxin resistant NaV subtypes. Both Compound 801 and ambroxol dose-dependently inhibited action potential conduction in guinea pig vagus nerves (assessed by compound potential), with ambroxol nearly 100-fold less potent than the NaV 1.7 selective Compound 801 in this and other NaV 1.7-dependent guinea pig and human tissue-based assays. Both drugs also inhibited citric acid evoked coughing in awake or anesthetized guinea pigs, with potencies supportive of an NaV 1.7-dependent mechanism. Notably, however, the antitussive effects of systemically administered Compound 801 were accompanied by hypotension and respiratory depression. Given the antitussive effects of topically administered Compound 801, we speculate that the likely insurmountable side effects on blood pressure and respiratory drive associated with systemic dosing make topical formulations a viable and perhaps unavoidable therapeutic strategy for targeting NaV 1.7 in cough.

Impact of Oral and Swallowing Function on the Feeding Status of Older Adults in Nursing Homes.

BACKGROUND: To date, there have been few guidelines proposed for adjustment of the food consistency, particularly to match the oral function of older adults, which will guide clinicians and caregivers in appropriately modifying food. OBJECTIVE: We investigated how oral, swallowing, and cognitive conditions of older adults who required daily nursing care in a nursing home were associated with different dietary food consistencies. METHODS: Clinical examinations to record dentition status, swallowing, and cognitive functions were performed, and the feeding status, including the food consistencies and need for assistance at lunchtime, was evaluated in 37 older residents in nursing homes. The swallowing function was assessed by performing a modified water-swallowing test, and food swallowing was tested using pudding and rice crackers. The χ2 test was used to determine the relationships among the parameters. RESULTS: No participants were able to take cooked rice, nor regular and soft side dishes. There was no significant relationship between dentition status and feeding status. Of the participants, 95% ate pudding without any problems and 49% ate rice crackers without any signs of swallowing difficulty such as coughing or stopping chewing. There was a significant relationship between the food test score using a rice cracker and the level of food consistencies, and between the same test score and the level of mealtime assistance, whereby the better the score of the food test using a rice cracker, the better was the level of food consistencies including use of a thickening agent and the better was the level of mealtime assistance. CONCLUSION: The results strongly suggest that the food test using a rice cracker was associated with the level of food consistency and mealtime assistance for older adults in nursing homes.